Biodiesel is produced via a reaction of vegetable oil or animal fat with an alcohol (usually methanol) and a catalyst. Biodiesel is chemically distinct from petroleum diesel and has a separate ASTM standard (D6751), which specifies the standard for biodiesel for use as a blend component with petroleum diesel. As approved by the United States Environmental Protection Agency, (“EPA”), the manufacture of biofuel has involved two conventional processes: transesterification and hydrotreating.
Transesterification involves the chemical replacement of glycerol in a triglyceride with an ester of an alcohol molecule. The process forms two principal products, fatty acid methyl esters or FAME, the chemical name for biodiesel, and glycerin. In this reaction, a vegetable oil or fat reacts with an esterifying agent, usually an alcohol, with or without a catalyst and with the input of additional energy, normally at atmospheric pressure. The reaction time can vary from about 0.5 to about 8 hours depending on the temperature and whether or not a catalyst is used.
Thus, transesterification typically proceeds slowly and generates a great deal of glycerol and some water which must be removed from the biofuel before it can be used. In addition to these byproducts, other byproducts such as alcohols, soaps, caustic agents and the like, may be present as a result of using excess reactants and catalysts to drive the reaction faster. If not removed, any of these byproducts may prevent the biofuel from being burned in a combustion engine or the byproducts may cause harm to the engine.
Hydrotreating is a process traditionally used by petroleum refineries to remove sulfur impurities from diesel fuel. Renewable diesel produced using this process can either be produced in a “bio-only” unit that uses only vegetable oils or animal fats as feedstock or where oils or fats are co-processed with the distillate fractions (diesel fuel) derived from petroleum. Both processes produce a mixture of hydrocarbons that has been reported to meet the ASTM standard for petroleum diesel (D975). The process also produces propane, carbon dioxide, and water from the oil/fat feedstock. However, hydrotreating has less desirable cold flow properties.
Accordingly, it is desirable to provide a method, device and system for manufacturing biofuel from renewable resources that is capable of overcoming the disadvantages described herein at least to some extent.